1. Field of the Invention
This invention relates to a method and apparatus for detecting knocking in an electronically controlled engine provided with a microprocessor.
2. Description of the Prior Art
Since vibration caused by knocking has a high frequency, it was necessary for prior knock detecting apparatus to detect mechanical vibration of an engine body or pressure in a combustion chamber with a knock sensor and analog-to-digital (A/D) convert the output of the knock sensor with a high speed A/D converter having, for example, a conversion time of several .mu. seconds for high speed processing of the A/D converted value with a CPU. The high speed type A/D converter and CPU were very expensive, placing the apparatus at a cost disadvantage.